Valid Argument/Examples/Trout have Wings

Example of Valid Argument

The following is a valid argument with false premises:

All trout are mammals.

All mammals have wings.

Therefore all trout have wings.

Proof

This is a categorical syllogism of the first figure, of the form $AAA$.

From Valid Patterns of Categorical Syllogism, this is seen to be a valid argument.

The premises, however, are false.

It follows that the argument, while valid, is unsound.

$\blacksquare$

Sources

• 1973: Irving M. Copi: Symbolic Logic (4th ed.) ... (previous) ... (next): $1$ Introduction: Logic and Language: $1.3$: Truth and Validity